By Cronic/Rexo

 // Overpower Proc Enabler - 60503
class spell_warrior_overpower_proc : public SpellScriptLoader
{
public:
    spell_warrior_overpower_proc() : SpellScriptLoader("spell_warrior_overpower_proc") {}

    class spell_warrior_overpower_proc_AuraScript : public AuraScript
    {
        PrepareAuraScript(spell_warrior_overpower_proc_AuraScript);

        bool CheckProc(ProcEventInfo& eventInfo)
        {
            //"Your other melee abilities have a chance to activate Overpower."
            //According to sources it should only proc on Whirlwind, Colossus Smash, Mortal Strike and Slam with a 5% chance.
            uint32 _spellId = eventInfo.GetSpellInfo()->Id;
            std::vector<uint32> spellList = { 1680, 167105, 12294, 1464 };
            for (auto id : spellList)
                if (_spellId == id)
                    return true;
            return false;
        }

        void HandleProc(AuraEffect const* /*aurEff*/, ProcEventInfo& eventInfo)
        {
            Unit* caster = GetCaster();

            if (!caster->HasAura(SPELL_WARRIOR_OVERPOWER_PROC))
                caster->CastSpell(caster, SPELL_WARRIOR_OVERPOWER_PROC, true);
        }

        void Register() override
        {
            OnEffectProc += AuraEffectProcFn(spell_warrior_overpower_proc_AuraScript::HandleProc, EFFECT_0, SPELL_AURA_DUMMY);
            DoCheckProc += AuraCheckProcFn(spell_warrior_overpower_proc_AuraScript::CheckProc);
        }
    };

    AuraScript* GetAuraScript() const override
    {
        return new spell_warrior_overpower_proc_AuraScript();
    }
};